It’s common to feel shaky after a vigorous workout. This can happen for several reasons, but it’s usually not a cause for concern.
Still, it’s important to know the difference between what’s normal and what’s not. In some cases, shaking after you’ve exercised might indicate a more serious problem. This is especially true if your tremors continue long after a workout.
If you’re prone to shaking after workouts, read on. We’ll explore the possible causes, plus ways you can prevent it from happening.
Because there are several possible causes of shaking after exercise, it’s important to take note of any other symptoms. Pay attention to your habits before and during your workout, too. This may help you pinpoint the reason behind your post-exercise shakes.
Let’s take a closer look at five of the most common causes for shaking after you’ve worked out.
1. Muscle fatigue
Muscle fatigue is a common reason for tremors after exercise.
During physical activity, your central nervous system (CNS) fires motor units to contract your muscles. A motor unit consists of a motor neuron and muscle fibers.
The firing of motor units provides force for your muscles. But the longer you work out, the more these signals slow down and become less intense. These changes can make your muscles rapidly alternate between contractions and relaxations, resulting in tremors.
Your CNS can also lose its ability to forcefully move your muscles. This can lead to fatigue, which may cause shaking or twitching.
Other signs of muscle fatigue include:
If you have muscle fatigue, it usually means you’ve worked your muscles to their max. That’s why you’re more likely to develop fatigue if you’ve challenged yourself with a tougher workout.
But sometimes, it might mean you’ve pushed yourself too hard. If you’re in pain or unable to finish your workout, try reducing the intensity of your exercise.
2. Holding a muscle in one position
This is due to the activity of motor units. Some motor units in your muscles are only used for powerful movements. When you hold a muscle in place for a long time, these motor units are activated to provide more force. This can result in shaking.
Typically, you’ll experience the tremors in the muscles being worked. For example, during or after planks, your arms and core may shake.
The same thing may happen when you lift and hold a heavy dumbbell.
3. Low blood sugar
Your muscles use glucose for fuel. When you work out, your glucose levels can become depleted, especially if you exercise at a vigorous pace or for a long period of time. This can lead to low blood sugar, also known as hypoglycemia.
Without enough fuel, your muscles may begin to shake. You might also experience:
Staying hydrated is important for keeping your electrolyte levels balanced. Electrolytes control the function of your nerves and muscles.
However, doing an intense activity can make you sweat a lot and lose water. The same goes if you exercise outdoors on a hot day.
If you sweat too much and become dehydrated, you may experience muscle twitching and cramps. This can feel like shaking.
Other symptoms of dehydration can include:
5. High caffeine intake
But if you consume too much, you may become jittery. The “high” you get from working out may make this even worse.
Shaking due to caffeine most often affects your hands and limbs, but it can involve other body parts. Excess caffeine intake may also cause:
Try these tips to reduce your shaking:
- Rest. Muscles often shake because they’ve been overworked. If you feel shaky, avoid jumping into another workout and let your muscles rest instead.
- Eat a healthy meal. Refuel your muscles by eating a post-workout meal. Focus on carbohydrates to replenish your glucose stores and protein to repair your muscles.
- Drink water. Be sure to rehydrate as soon as possible to restore your electrolyte and fluid levels.
- Stretch. Stretching after you’ve worked out may help loosen your muscles and reduce spasms, aches, and cramps.
It’s also possible to prevent post-exercise tremors before they happen. Here’s how:
- Challenge yourself gradually. Increase the duration or intensity of your workout in small increments. This may help prevent shaking and injury.
- Eat a pre-workout meal. Give your body enough fuel before you start exercising. Consume a pre-workout meal 2 to 3 hours before your workout.
- Limit or avoid caffeine. If you’re sensitive to caffeine, reduce or avoid it before exercise.
- Warm up and cool down. Before exercise, warm up to prepare your muscles for movement. Cool down when you’re done to promote recovery and reduce soreness and fatigue.
- Prepare a post-workout meal in advance. If you have a meal prepared ahead of time, you can quickly and easily refuel your muscles once you’re done working out.
- Hydrate before, during, and after exercise. Drinking fluids throughout the day can help reduce your risk of dehydration. Increase your fluid intake if you exercise outdoors in hot weather, or if you do a strenuous workout.
In most cases, post-workout shaking isn’t serious. But if you notice any of the following symptoms, get medical help:
Muscle fatigue, dehydration, and low blood sugar are common reasons for post-workout shaking. It can also happen when you hold a muscle in one position for a while, like during a plank. Drinking too much caffeine before working out may make you feel jittery or shaky, too.
To prevent tremors after exercise, avoid pushing yourself too hard. Stay hydrated throughout the day and eat a healthy post-workout meal. If you experience shaking long after exercise, or if you shake when you’re not exercising, it’s a good idea to follow up with your doctor or healthcare provider.